Blend file opens in 32 bit but not 64 bit?
Have you unchecked the "load UI" option box before opening the file? I have had occasional problems opening files created with different versions that were ignored when I used the current user interface rather than the one embedded in the .blend file.

I tried the sensei interface and went back within a couple of hours... Too much of a change from what I was accustomed to using to adapt.

Phred